Conductive
– Occurs when sound is impeded through external ear, middle ear or both.
External ear
Wax build up (cerumen)
Causes hearing loss when it completely occludes ear canal.
Wax produced by ceruminous glands in outer ear migrates laterally along meatus.
Too much build-up can impact ear canal. Use of cotton wool buds to clean ears can cause impaction too.
Patient complains of hearing difficulty, irritation in ear, dark brown, shiny, soft mass.
Confirmed by: improvement in hearing after wax removal.
Foreign body
Adults may get a foreign body in attempt to clean ear with match sticks or cotton buds.
Suggested by: visible foreign body and inflammation
Confirmed by: retrieval of foreign body using forceps or irrigation.
Otitis Externa (Swimmer’s ear)
Diffuse inflammation of skin lining outer ear canal.
Bacterial or fungal (otomycosis)- most common are staph pyogenes, staph aureus, diphteriods, and pseudomonas aeruginosa
Some people prone to this due to narrow external canal.
Pain on manipulation of pinna, ear canal is edematous and filled with infectious debris that occlude canal.
Exostosis
Benign bony growth that may cause wax or debris buildup
Suggested by: palpable bony projections in ear canal, history of swimming in cold water (unknown reason), accumulated wax difficult to clear.
Bone growths appear sessile, smooth, often bilateral.
Osteoma
Single and unilateral benign bony growths found at bony cartilaginous junction.
Other uncommon causes- sebaceous cysts, tumours (fibromas, papillomas, adenomas, sarcomas, carcinomas and melanomas), occurs in elderly, if spread to invade middle ear, facial nerve and temporomandibular joint, it causes extreme pain with blood-stained discharge from ear.
Middle ear
Tympanic membrane perforations
Due to water accidents, explosions, penetrating injury, or temporal bone fractures.
In acute setting, blood may obstruct ear canal and prevent visualisation of membrane.
Acute otitis media
Acute inflammation of middle ear due to pneumococcus, haemophilus, strep and staph bacteria.
Rapid onset after hours of throbbing, severe pain, and fever, irritability.
Bulging red drum, or profuse purulent discharge.
Chronic otitis media
Painful loss of hearing, narrow canal with red, immobile tympanic membrane.
Middle ear effusions decrease mobility of tympanic membrane results in hearing loss of 20-30 dB.
There’s watery discharge, bilateral symptoms, erythema and weeping of meatus.
Trauma
Direct- poking in ear with sharp implements ( hair clips)
Indirect- pressure from slap with open hand, blast injury, temporal bone fracture, welding sparks.
Bleeding from ear, blood clot in ear canal, a tear in tympanic membrane.
Cholesteatoma
Accumulation of squamous epithelium in middle ear.
May be seen in patients with otitis media
Foul discharge, deafness, headache, ear pain, facial paralysis and vertigo.
Retracted or perforated tympanic membrane with chronic drainage.
Otosclerosis
Abnormal bone deposition at the footplate (base of stapes), leads to fixation of stapes at oval window, preventing vibration.
Presents as progressive bilateral conductive hearing loss
Sensorineural
- disorders that affect inner ear and neural pathways to auditory cortex
- most patients: adult
- children: - hereditary & non-hereditary congenital hearing loss
Bilateral hearing loss
1. Presbycusis
- symmetric, progressive deterioration of hearing in elderly patients
Etiology
- combination of inherited and environmental factors (lifetime noise exposure and tobacco use)
Effect
- high frequency hearing and speech discrimination
2. Noise trauma (most common)
Source
- occupational, recreational, accidental
- gunfire, explosions, loud music
Effect
- high frequencies affected first (4000Hz), then middle and lower frequencies
- high-pitched tinnitus
3. Ototoxin exposure (less common)
Source
- diuretics, salicylates, aminoglycosides, chemotherapeutic agents
Effect
- hearing loss or dizziness
4. Autoimmune hearing loss
S&S
- rapidly progressing bilateral sensorineural hearing loss
- poorly speech discrimination scores
- vertigo
- disequilibrium
- symptoms improve with administration of oral prednisone (best way to make the diagnosis)
Unilateral hearing loss
1. temporal bone fractures
Etiology
- fracture line involves bony labyrinth (cochlea or vestibule)
S&S
- facial nerve paralysis
- CSF leakage
- intracranial injuries
2. Perilymph Fistula
Etiology
- rupture of round or oval window membranes, with perilymph leaking into middle ear (fistula)
- straining, lifting, coughing, sneezing
S&S
- abrupt loss of hearing
- vertigo
- tinnitus
Management
- 3-6 weeks of bed rest
- surgical repair if symptoms doesn't improve
3. Meniere's disease
Etiology
- unclear BUT
- endolymphatic hydrous (increased fluid pressure within inner ear)
S&S
- unilateral fluctuating hearing loss (initially: low frequencies, as disease progresses: higher frequencies)
- aural fullness
- tinnitus
- episodic vertigo
Treatment
- low-salt diet
- diuretics
- vestibular suppressants
- hearing aids INEFFECTIVE because patients suffer from poor speech discrimination as well as diminished tolerance to amplified sound
4. Idiopathic unilateral sudden sensorineural hearing loss
- hearing loss of 30 dB within a three-day period
Etiology
- viral infections and vascular insults
- rarely perilymph fistulas & acoustic neuroma
- viral etiology - history of upper respiratory infection within a month of hearing loss
S&S
- tinnitus
- vertigo
- aural fullness
5. Acoustic neuroma
Etiology
- non-cancerous tumor that develops on the nerve that connects the ear to the brain (CNVIII)
- grows slowly
- presses against nerve
S&S
- unilateral sensorineural hearing loss
- ringing in ears (tinnitus)
- dizziness (vertigo) and balance problems
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